5HT1A is the intronless coding locus (1266 base pair - 422 amino acids) for a G protein-coupled serotonin receptor with a typical 7-transmembrane structure, located on chromosome 5 in humans. Previous work in this laboratory discovered two variants (Biochem Biophys Res Commun 1995;210(2):530-6), characterized their frequency and distribution in human populations (Human Mutation 1996;7:135-43) and investigated their functional effects (Neuropsychopharmacology 1997; 17:18-26). In order to assess the polymorphic spectrum of this locus in a primate animal model heavily used in neuroscience research, we have cloned and sequenced the highly conserved 5HT1A gene from four macaque species (Macaca fascicularis , Macaca maura, Macaca mulatta and Macaca nemestrina) and from the vervet monkey (Cercopithecus aethiops). Both interspecific and intraspecific sequence variations have been discovered, the interspecific variation supporting the known phylogeny of Macaca, while the intraspecific variation will be characterized in a large group of Macaca mulatta for which serotonin metabolites and behavioral data exist in order to assess potential association between serotonin receptor variants and behavior.